Meaning & use
supplementary line
An extra line added to a geometric figure to help solve a problem or complete a proof, not part of the original figure.
See it in a sentence
The teacher drew a supplementary line connecting the two triangles to reveal a hidden right angle.
Adding a supplementary line often turns a difficult geometry proof into a simple one.
A note on using this word
Do not confuse this with "supplementary angles," which are two angles that add up to 180 degrees; a supplementary line is a drawing aid, not an angle relationship.
Words with a similar meaning
auxiliary lineconstruction line
Choose a synonym to suit the sentence. Meanings can overlap without being identical.
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